1. Technical Field
The present invention relates to submarine network's, and more particularly, to secure WSS-based reconfigurable branching units for submarine networks.
2. Description of the Related Art
Submarine optical networks form the backbone of global communication networks, and generally include main trunks that connect trunk terminals (e.g., point-to-point cable links with in-line optical amplifiers to boost the signal power), and branch paths which connect to other branch terminals. A branching unit (BU) is a network element that splits the signal between the main trunk and the branch path and vice versa. This allows the signals from different paths to share the same fiber instead of installing dedicated fiber pairs for each link. BUs generally perform signal splitting and combining functions optically, and thus the BU has a similar function as an optical add/drop multiplexer (OADM) in terrestrial wavelength division multiplexing (WDM) networks.
Existing BU and submarine networks have fixed, pre-determined wavelength arrangements, and thus no reconfiguration is required after installation. However, a disadvantage of this arrangement is that the traffic in the global communication network is becoming more dynamic as internet-based traffic becomes more dominating. There have been efforts to add reconfigurability to networks, including employing tunable optical filters, replacing a single optical filter with an array of filters, and employing a wavelength-selective switch. However, each of the above-mentioned approaches includes drawbacks (e.g., limited quantity of BU configurations, added complexity to the BU, no full reconfigurability of BU, security issues, etc.), which are not desirable in submarine networks.